Speciation of BC _x N _y films grown by PECVD with trimethylborazine precursor

摘要

Films of BC _x N _y were produced in a plasma-enhanced chemical vapor deposition process using trimethylborazine as precursor and with H_2, He, N_2, and NH_3, respectively, as auxiliary gas. These films deposited on Si(100) wafers or fused quartz glass substrates were characterized chemically by X-ray photoelectron spectroscopy and by synchrotron radiation-based total-reflection X-ray fluorescence combined with near-edge X-ray absorption fine structure. Independent of the auxiliary gas, the B-N bonds are dominating. Furthermore, B-C and N-C bonds were identified. Oxygen, present in the bulk (in contrast to the surface layer of some nanometers, where molecular oxygen and/or water are absorbed) as an impurity, is bonded to boron or to carbon, respectively. The relation of boron and nitrogen changes with the character of the auxiliary gas: c _B/c _N ≈ 4:3 (for H_2 and He) and c _B/c _N ≈ 1 (for N_2 or NH_3). Furthermore, physical properties such as the refractive index and the optical band-gap energy were determined.